Motor-compressor

ABSTRACT

THE INVENTION RELATES TO A MOTOR-COMPRESSOR ASSEMBLY OF THE TYPE USED FOR SMALL REFIGERATING MACHINES. THE ASSEMBLY HAS A VERTICAL CRANKSHAFT ARRANGEMENT WITH A CARRIER FRAME BEING FORMED WITH RADIAL AND AXIAL THRUST BEARINGS TO PROVIDE LATERAL AND VERTICAL SUPPORT FOR THE CRANKSHAFT. A DETACHABLE BEARING MEMBER IS ATTACHED TO THE UPPER PORTION OF THE CRANKSHAFT WHICH HAS AN ANNULAR BEARING SURFACE FOR ENGAGEMENT WITH SAID AXIAL THRUST BEARING AND COMPENSATING WEIGHT MEANS FOR COUNTERBALANCING THE CRANK PORTION OF THE CRANKSHAFT.

United States Patent [72] Inventors goes: Mlhncke 3,125,184 3/1964Valbjarr 230/206X Km vm'ahlbjomNordm Denmark Primary Examiner-Robert M.Walker W No. 836.013 Attorney-Wayne B. Easton [22] Filed June 24, 1969[45] Patented June 28,1971 [731 Assignee Danfoss AIS, Nordborg, Denmark54 uo'ron-comasssoii I 5 Claims, 5 Damn Figs ABSTRACT: The inventionrelates to a motor-compressor assembly of the type used for smallrefrigerating machines. The Cl assembly has a vertical crankshaftarrangement with a carrier Ill. frame being formed with radial and axialthrust bearings to MOT provide lateral and vertical upport for thecrankshaft A 1721 205; 74/573 603; 363 detachable bearing member isattached. to the upper portion I 5 6] References Cited of the crankshaftwhich has an annular bearing surface for engagement with said axialthrust bearing and compensating UNITED STATES PATENTS weight means forcounterbalancing the crank portion of the 3,l04,05l 9/1963 Herring etal230/206 crankshaft.

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T if T H 2 PATENTED JUN28 1971 SHEET 1 BF 2 FIG PATENTEDJUN28I9YI 357343 sum 2 or 2 FIG 3 FIG 4 since the space around the shaft is limited.Furthermore,

reliance has to be placed upon each crankshaft providing balancedoperation after its manufacture; any unevenness subsequently observedcannot be eliminated.

The object of the invention is to provide a motor compressor of theabove-described kind, in which the problem of dynamic balancing issolved in a considerably better manner than hitherto.

According to the invention, this object is achieved by securing to oneend face of the shaft a disc which, outside an annular portion extendingbeyond the diameter of the shaft and forming an axial bearing, has anadditional part ring as a compensating weight on the side opposite thecrank.

In this arrangement, the compensating weight is combined with an axialbearing in such manner that the center of gravity of the compensatingweight is located at a relatively great distance from the axis ofrotation of the shaft. Consequently, a relatively small weight suffices;since the weight is located at an end face of the shaft, the disc canalso be made to any thickness and thus suited to the compensating weightrequired.

A further possible way of suiting the compensating weight consists insecuring at least one further annular portion on the part ring. In thisway, a single type of axial bearing disc can be related to a pluralityof different crankshafts.

Expediently, the axial bearing is formed at the end face of a radialbearing and the further annular portion surrounds the radial bearingbush. In this manner the axial dimension of the construction is reduced.Also, the end face of the compressor housing can be set back around theradial bearing bush to form an annular recess. The compensating weightarrangement is then well protected against mechanical damage.

In a preferred form of construction, the disc is detachably secured tothe end face of the shaft, for example by means of a screw. This createsthe possibility of exchanging the disc for one having a differentcompensating weight.

It is particularly advantageous if a further compensating weight isprovided on the rotor by creating an enlarged portion on theshort-circuiting ring facing the crank and on that side of the ringopposite the crank.

This constitutes a simple method of providing a compensating weight oneach side of the crank, thus achieving particularly good balancing. Themotor crankshaft itself does not need to carry any compensating weightat all. Therefore, depending upon circumstances, the crank bearing canbe pushed on from either end of the shaft if, between the middle portionof the shaft and the crank, there is present a neck portion of smallercross section, which enables the crank bearing to be radially offset.

An embodiment of the invention will now be described in some detail byreference to the drawing, in which:

FIG. 1 shows a longitudinal section through a motor compressor inaccordance with the invention,

FIG. 2 shows a central partial section through the upper end of themotor compressor on a plane at right angles to that of FIG. 1,

FIG. 3 is a view from below of the centrifuging disc used,

FIG. 4 is a view from below of the axial bearing disc employed, and

FIG. 5 shows a section through the motor crankshaft, on the line A-A ofFIG. 1.

The motor compressor is mounted in a case 1 by means of springs, notillustrated. In the lower part of the case is an oil sump 2. An oildelivery pipe 3, the lower end of which is formed as" a hollow cone 4,extends into this sump. The delivery pipe 3 is pressed into a bore 5 ina motor shaft 6, which drives a compressor piston, not illustrated,through a crank 7, a crank bearing 8 and a connecting rod 9. The shaft 6is supported in a first radial bearing 10, which is formed in thecarrier element 11 for the motor, and in the second radial bearing 12,which is formed in an insert 13 in the carrier member 11. An axialbearing is formed by the underside 14 of a disc 15 secured to the endface of the shaft 6, in conjunction with the upper end face of theradial bearing bush 12. Above this is located a centrifuging disc 16.The two discs 15 and 16 are detachably secured to the shaft 6 by meansof a screw 17 and are held against rotation with the help of a pin 18.The motor consists of a stator 19, connected to the carrier member 11,and a rotor 20 connected to the :shaft. The upwardly extending wall 21of the carrier member 11, together with the insert 13, formsnoise-reducing chambers 22.

The oil delivered by the pipe 3 rises in the bore 5 of the shaft 6; partof it is deflected through a bore 23 for the lubrication of the radialbearing 10. The rest passes farther upwards through three axiallyparallel bores 24, 25 and 26, the positions of which can be seen fromFIG. 5. Oil is diverted through a transverse bore 27 for lubricating thecrank bearing 8. The oil emerging from the three bores 24, 25 and 26passes into an opening 28 in the disc 15. From here, oil can bedistributed through a radially extending groove 29 over the surface ofthe axial bearing at the underside 14 of the disc. The rest of the oilpasses through a cutaway portion 30 in the edge of the centrifuging discto the edge 31 thereof and is flung on to the wall of the casing by therim 32.

As FIG. 3 shows, the centrifuging disc 16 has an upwardly inclined edge31 over only somewhat less than half of its circumference and on thatside where the three bores 24, 25 and 26 run out of the end face of theshaft 6. The lower rim 33 of the edge 31 is located below the underside14 of the disc 15. The rim 32 is positioned above the end face of theshaft arrangement, i.e. of the cutaway portion 30 in the centrifugingdisc 16, and also above the upper end face of the carrier member 11;consequently, the oil emerging near the axial bearing is caught andpassed to the wall of the case, although this point is positioned belowthe end face of the carrier member.

The disc 15 is provided on the side opposite the crank with anadditional part ring 34 to which is also fitted, by means of rivets 36,a further annular portion 35.

For the sake of clarity, one of the rivets 36 is sectioned in FIG. 2. Inthis way there is created a compensating weight by means of which theimbalance caused by the crank 7 can be offset. Around the upper radialbearing bush 12 is located an annular space 37 in which a'portion 38 ofthe end face of the insert 13 is set back. This annular space canaccommodate not only the one further annular portion 35 illustrated,but, if required, a second such portion. It is clear that these annularportions do not lie precisely opposite to the edge 31 of thecentrifuging disc, so that the two parts cannot collide with each other.

For the purpose of further balancing of weight, the uppershort-circuiting ring 39 of the rotor 20 is provided with an enlargedportion 40 over half of its circumference on the side opposite thecrank. In this way a compensating weight is provided above and below thecrank 7, so that the arrangement has extremely little imbalance.

The disc 15 can be fitted after the motor compressor has been assembled.There is no difficulty in adding additional weights or in achievingoptimum dynamic balance by changing one disc for another.

In assembling the system, the crankshaft is pushed up onto the shaft 16from below and is offset radially in the neck portion located below thecrank 7 to an extent such that it can be pushed onto the crank. Theshaft is then fitted on to the carrier member 1] from above and therotor 21 is pressed on from below. The cup-shaped insert 13 is thenpressed into the carrier member 11 from above, and finally the bearingdisc 15 and the centrifuging disc 16 are screwed on tight at the top.

We claim:

l. A motor-compressor assembly comprising a casing, a carrier framedisposed internally of said casing, said frame defining a radial bearingand an upper axial bearing, a shaft rotatably joumaled in said radialbearing, a shaft-supporting disc member attached to said shaft andengaging said axial bearing, said shaft having a crank portion betweensaid bearings, said shaft-supporting disc member having compensatingweight means extending radially therefrom in the opposite directionrelative to said crank portion.

2. A motor-compressor assembly according to claim 1 ineluding alubricating disc member attached to the upper side

